For a portable information processing apparatus such as a notebook type computer, it is an important object to protect the information processing apparatus from a shock effected if the apparatus is inadvertently dropped or jarred while being carried or operated. In particular, the structure of a magnetic disk device commonly used as a storage device for an information processing apparatus of this kind is susceptible to a shock or vibration. It is thus desirable to provide an effective protection mechanism.
The magnetic disk device causes a magnetic head to seek a rotating magnetic disk to write or read data to or from the disk. Accordingly, if the magnetic head collides against the magnetic disk, the magnetic disk may be damaged to hinder part or all of the data from being restored. Therefore, the shock resistant performance of the magnetic disk device can be improved by causing the magnetic head to “escape” from the magnetic disk before a shock or vibration occurs.
As a protection mechanism of this kind for the conventional magnetic disk device, the magnetic disk device comprises a sensor for detecting that the magnetic disk device is inclined, and an escape control means for determining that the magnetic disk device is inclined on the basis of a detection signal from the sensor, to move the magnetic head to an escape area. In this case, the inclination of the magnetic disk device is detected as a sign of fall of the magnetic disk device to cause the magnetic head to escape from the magnetic disk (for example, refer to Patent Document 1, below).
Further, the magnetic disk device has hitherto been provided with a self-diagnosis function as its protection mechanism. A typical self-diagnosis function is a S. M. A. R. T. (Self-Monitoring Analysis and Reporting Technology) which provides various information on a spin up time, write errors, a seek rate, and temperature and which can predict the possibility of a failure (for example, refer to Non-Patent Document 1, below).
[Patent Document 1]
Published Unexamined Japanese Patent Application No. 2629548 (P. 1 to 3, FIG. 1)
[Non-Patent Document 1]
“Information Technology—AT Attachment with Packet Interface—5 (ATA/ATAPI-5)”, [online], Feb. 29, 2000, Technical Committee T13, (p. 39 to 41).
According to the conventional technique described in Patent Document 1, the magnetic head escapes if an output from a pressure sensor that detects a change in the weight of the magnetic disk device indicates that a portable terminal apparatus in which the magnetic disk device is mounted is markedly inclined or that the apparatus has started to fall. However, this escape condition is abstract and is not definite. Accordingly, it is undeniable that there is a possibility of detecting the inclination of the portable terminal apparatus which does not actually lead to a fall to unnecessarily cause the magnetic head to escape as in the case in which, for example, a notebook type computer is used on a user's lap. In this case, every time the portable terminal apparatus is inclined, the magnetic head escapes from the magnetic disk. Consequently, in a practical sense, this conventional technique hinders the apparatus from being easily operated.
Further, Patent Document 1 does not describe any conditions for returning the magnetic head if it has been mistakenly caused to escape.
Further, the S. M. A. R. T.-based self-diagnosis function for the magnetic disk device does not determine whether or not a particular shock has damaged the magnetic disk device but evaluates faults using accumulated statistical information on the whole magnetic disk device. Accordingly, the S. M. A. R. T. self-diagnosis provides only such information as indicates that the incidence of an error or the like has exceeded a threshold, indicating that a failure is likely to occur. Furthermore, even if a shock to the magnetic disk device damages part of a magnetic recording area on the magnetic disk device, the presence of this damaged area cannot be noticed until the area is accessed if the S. M. A. R. T. is used in a normal manner.
It is thus an object of the present invention to provide a magnetic disk device protection mechanism which allows a magnetic head escape condition to be set in detail and which is thus effective and practical.
It is another object of the present invention to provide a self-diagnosis for determining, if the magnetic disk device is shocked, whether or not the shock has damaged the magnetic disk device.